Polar bears in the southern Beaufort Sea may be turning to cannibalism because longer seasons without ice keep them from getting to their natural food, a new study by American and Canadian scientists has found.
The study reviewed three examples of polar bears preying on each other from January to April 2004 north of Alaska and western Canada, including the first-ever reported killing of a female in a den shortly after it gave birth.
Polar bears feed primarily on ringed seals and use sea ice for feeding, mating and giving birth.
Polar bears kill each other for population regulation, dominance, and reproductive advantage, the study said. Killing for food seems to be less common, said the study's principal author, Steven Amstrup of the U.S. Geological Survey Alaska Science Center.
The reality or unreality of global warming notwithstanding, I don't know if I believe that polar bear numbers or polar bear behavior are adequate indicators of it. I find it somewhat distressing that they have become a political football in this. I read conservative columnists asserting that polar bear numbers are increasing, and I think that both that and articles like this one are muddying up the issue.
I am no expert, but I feel like a degree of cannibalism is not uncommon in most species. Can someone who knows more about this clarify that for me?
In any case, let's leave polar bears out of it and try and focus on the data concerning global warming. I know they are cute, but let's try not to be rhetorical.
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I'm not an animal behavior expert either but I believe the most common incidents of cannibalism among mammals are cases of infanticide of young to which they are not closely related. I don't actually know that infanticide, among dolphins for example, involves the consumption of the young, but prairie dogs for example do often eat un-related young. A (male?) polar bear attacking a fully grown female is odd, and I would think probably the result of scarcity. I'm not sure I'd leap from there to say global warming is the cause.
While it is true not a lot can be concluded from a few isolated examples of stressed polar bears -- and there is nothing particularly interesting in a few cases of cannibalism among polar bears, I think there is value in presenting such stories as examples of the potential effects of climate change.
It's like hurricane frequency; so long as you don't claim a causal connection right now, but use the effect to illustrate why we should be worried about the future, then I don't see a problem.
I reviewed the literature at Thoughts from Kansas.
I agree with James in that we need all of the facts whether we know they're related or not. Since we've seen an increase in polar bear drownings that seem to be related to the loss of ice used by the species...
If we suspect something is related to climate change, whether anthropogenic global warming or otherwise, shouldn't we mention it regardless of personal preferences? I'd rather have too much information, even if some of it ultimately does not apply, than have too little information and find out too late that things should have been linked much earlier.
Ultimately, unless there is ample scientific evidence or reason to negate a theory (e.g. intelligent design/creationism), let's not censor what scientists say. Our government does a fine job of that already.
I am not suggesting that we censor anything.
Perhaps I wasn't making myself clear. My concern with this business is that polar bear numbers is a poor scientific indicator of global warming but an excellent rhetorical club in the global warming debate.
I want to make sure that it does not become a distraction from the other more climate-based science, but from the comments I think I am getting that people understand the two are not equivalent -- which is reassuring.